Valves for causing overlapping engagement of clutches

ABSTRACT

A fluid power control system for a vehicle having forward, reverse and speed range clutches, and the vehicle being driven from a source of power, such as an internal combustion engine, through a torque converter, which is controlled by a fluid actuated and modulated main clutch. The control system (FIG. 4) includes cross-over valve means connected with the direction clutches and the speed change clutches so that when a shift from one clutch to the other is called for by the action of the operator, the clutch which had been engaged is held in engagement until the newly selected clutch is at least partially engaged, and then the clutch which had been engaged is released. The system eliminates heat generation which is otherwise caused by slow shifting which in turn permits the vehicle power source to build up inertia energy in the power input parts, such as the flywheels, main clutch and torque converter.

United States Patent Hilpert Oct. 2, 1973 KIA/6: (l 070/ 4! VALVES FOR CAUSING ()VERLAPPING ENGAGEMENT OF CLUTCHES Conrad R. Hilpert, Winnebago, 111.

Twin Disc, Incorporated, Racine, Wis.

Filed: Apr. 3, 1972 Appl. No.: 240,710

Related U.S. Application Data Division of Ser. No. 66,282, Aug. 24, 1970, Pat. No, 3,692,160.

Inventor:

Assignee:

U.S. Cl. l92/87.l3, 74/745, 192/109 F, l92/3.57, 137/625.63

Int. Cl. F16d 25/10 Field of Search 192/87.l3, 87.18, 192/87.19, 3.26, 3.27, 3.32

References Cited UNITED STATES PATENTS ///6// #010 has; fol/V410 I/Pl) Fez.

Primary ExamineF- Benjamin W. Wyche All0rneyJames E. Niles [57] ABSTRACT A fluid power control system for a vehicle having forward, reverse and speed range clutches, and the vehicle being driven from a source of power, such as an internal combustion engine, through a torque converter, which is controlled by a fluid actuated and modulated main clutch.

The control system (P10. 4) includes cross-over valve means connected with the direction clutches and the speed change clutches so that when a shift from one clutch to the other is called for by the action of the operator, the clutch which had been engaged is held in engagement until the newly selected clutch is at least partially engaged, and then the clutch which had been engaged is released. The system eliminates heat generation which is otherwise caused by slow shifting which in turn permits the vehicle power source to build up inertia energy in the power input parts, such as the flywheels, mainclutch and torque converter.

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sum 01 or 18 PATENTEDHBT 2 1 saw 02 nr 18 PATENTEUUEI 2191s sum ow 1a WHEN I EU 2 5 SHEET 05 0F 18 PATENTEDBBT elm SHEET 10 0F 18 PATENTED OCT 2 saw 12 nr 18 PATENTED 2|975 arm v1am 1a PATENTED 2 9 5 saw 1a of 1a SESE PATENTED 2 73 sum 1a or 1B VALVES FOR CAUSING OVERLAPPING ENGAGEMENT OF CLUTCHES CROSS REFERENCE TO RELATED APPLICATION This application is a divisional application from the U. S. application Ser. No. 66,282 filed Aug. 24, 1970 entitled, Fluid Power Control System For Vehicles and now US. Pat. No. 3692160, issued Sept. 19, 1972.

BACKGROUND OF THE INVENTION The invention pertains to fluid power control systems for vehicles, for example, those which operate in either direction, such as front end, earth moving loaders or the like. These control systems control the shifting of fluid clutches for changing the direction of travel of the vehicle as well as its speed in either direction. The transmissions used with such vehicles also include a torque converter which is driven from a power source through a modulatable and fluid actuated friction clutch. Considerable heat is generated in the clutches when shifting from one to the other is made at excessive vehicle speeds, and the control system of the present invention substantially eliminates this heat generating, as well as eliminating a second source of heat which is generated during the neutral gear position and which is due to the inertia of the moving parts of the transmission. This second source of heat in the clutches is caused by slow shifting of the clutches which permits the power source to store inertia energy in the input parts and permits the driven vehicle to be without driving torque and thereby slow down, thus increasing the heat dissipation forspeed range to speed range shifts.

SUMMARY OF THE PRESENT INVENTION The present invention provides a fluid power control system for a vehicle which has brake, forward, reverse, and speed range clutches, and which vehicle is driven from a source of power, through a torque converter which in turn is controlled by a fluid actuated and modulated main friction clutch. The control system provided by the present invention includes inhibitor valve means which functions to inhibit the shifting of the clutches between forward and reverse directions and also inhibits speed gear shifting in a downward direction above a predetermined speed. The inhibitor valve means functions to actually apply the vehicle brakes is to be made, the clutch which had been engaged is v I held in engagement until the newly selected clutch is commencing to be or is at least partially engaged, and then the clutch which has been engaged is released. The control system eleiminates heat generation which is otherwise caused by slow shifting which in turn permits the vehicle power source to build up inertia energy in the power input parts, such as the flywheels, main clutch, and torque converter. The cross-over valves provided by the present invention eliminate the heat build up which is due to the conventional neutral position of the gears, and the cross-over valves are effective regardless of how slowly the clutches are shifted.

The present invention provides a fluid power control system for a vehicle which insures complete heat control of the clutches and torque safety of the transmission, combined with complete operator control and smooth shifting in either direction and at all speeds.

' These and other objects of the present invention will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fluid circuit diagram embodying the present invention and showing the inhibitor valve means as a box;

FIG. 2 is a more or less schematic diagram of the inhibitor valve means which is simply shown as a box in FIG. 1;

FIG. 3 is a fluid circuit diagram of one form of the fluid pressure supply circuit which is connected to the circuit of FIG. 1; I

FIG. 4 is an enlarged view of theright hand portion of the FIG. 1 circuit, namely, the cross-over valve means;

FIG. 5 is an enlarged, more or less schematic view, of each of the foot pedal valves 35, 36 and 37 shown at the lower'left end of the FIG. 1 circ'uit;

FIG. 6 is a schematic view of the foot control and hand shifting format for operating the various brake, forward and reverse foot operated valves, and the change speed gear valves;

FIG. 7 is a schematic view of a power transmission for a vehicle and with which the control system of the present invention is usable;

FIG. 8 is an enlarged, schematic cross sectional view of the main clutch control valve FIGS. 9 through 20 are diagrams showing the portions of the circuitry that are used for various shifting operations, as follows:

FIG. 9 is a circuit showing the power take off operation;

FIG. 10 is a circuit showing the low speed forward steady operation;

FIG. 11 is a circuit showng the 'low speed forward at the time of. a demand for backward motion;

. FIG. 12 is a circuit showing the cross over terminating; v

FIG. 13 is a circuit showing the high speed forward steady; v

' FIG. 14 is a circuit showing the high speed forward and call for downshift;

FIG. 15 is a circuit showing the high speed forward call for backward;

FIG. 16 is acircuit showing the high speed call for brakes; 1

FIG. 17 is a circuit showing the medium speed called for downshift;

FIG. 18 is a circuit showing the cross over terminated; I

FIG. 19 is a circuit showing the medium speed forward and call for backward; and

FIG. 20 is a circuit showing neutral.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be shown and described as 

1. A vehicle having a gear speed shift mechanism including a pair of fluid actuated gear shift clutches, and also having fluid pressure circuit means for actuating said clutches, said circuit means including a fluid pressure operated shiftable control valve having a shiftable portion for each of said gear shift clutches, said shiftable control valves each having a first operating pilot at one end and a larger operating pilot at the other end for shifting their respective shiftable portions, a high hold pressure line connected to each of said shiftable control valves and communicable with said portion, an apply pressure line connected to each shiftable control valve and communicable with said portion, a pair of cross-over fluid circuits each connected between said first operating pilot of one of said shiftable control valves and the larger operating pilot of the other control valve, each of said cross-over fluid circuits also communicable with said shiftable portion of a control valve and one of said clutches, a check valve between each apply line of one control valve and that cross-over circuit which is connected to the larger operating pilot of said other control valve, and control means for selectively applying fluid pressure to each of said apply pressure lines. 